1. Field of the Invention
The present invention is in the field of building structures and construction techniques and more specifically, relates to a structure used for storing commodities.
2. The Prior Art
The structure described herein can be used advantageously for storing a wide variety of particulate commodities including, but not limited to, grains, cement, crushed rock, pelletized materials and chemicals. The most likely application of the invention is for use as a chamber in which grain or feed can be stored.
For long-term storage, whole grain is typically stored in large tanks or silos having a capacity of 2,000 to 5,000 tons. This grain is eventually milled for use in making various mixtures of grains for use as feed. After some of the grain has been removed from the large tank, it is milled and then stored in a working bin, from which it is drawn as desired for mixing with other milled grains to produce a feed of desired proportions. The working bin typically holds 60 tons of ground or powdered commodity and includes means for delivering a metered amount to a weigh hopper. The present invention relates to a novel construction for working bins.
Wood and concrete are not desirable for use as working bins, although they were used in the past. Working bins of wood and concrete tend to absorb moisture and to transfer the moisture to the grain which generates a gas which can explode. Also, concrete and wood structures cannot get rid of static electricity as easily as metallic structures. For these reasons, most modern working bins are of metallic construction.
Grain stored in a working bin exerts considerable sideward force on the walls of the bin, tending to cause them to bulge out. For this reason, the walls are almost universally made of corrugated metal with the corrugations extending in a horizontal direction. Unfortunately, most types of stored material and particularly soy beans tend to hang up on the horizontal corrugations as the stored material is drawn from the working bin. Also, a dust of the stored material tends to collect on the corrugations above the stored material. In addition to presenting problems of cross-mixing when a different material is later stored in the same working bin and the practical difficulties in sweeping the dust from the corrugations in a 45-foot tall chamber, the tendency for the material to collect on the corrugations prevents a serious hazard.
It is well known that finely-divided substances tend to be more readily oxidized and some materials such as alfalfa dust or cornstarch are especially explosive. For all of the above reasons the use of horizontally extending corrugations is not desirable.
Most corrugated metal is manufactured in rolling mills and hence the width of the sheets supplied is limited by the width of the rolling mill. Consequently, when the corrugations are to be oriented horizontally, it is necessary to form a wall by joining a number of corrugated sheets. In one form of construction known in the art, the corrugated sheets are attached by bolting or welding to the metal frame of the structure. This technique has the disadvantage that most of the assembly is done in place, and there is no possibility of pre-assembling large modular sections on the ground. As a result, this type of prior art construction results in higher labor costs for a bin of given size.
In view of the aforementioned disadvantages of the prior art structures and construction techniques, it is apparent that a long-felt need exists in the industry for a working bin which can be constructed at minimum cost and which will have smooth interior walls to avoid the hazard associated with the corrugated walls conventionally used.